Summary This continuation research proposal (in its 12th year) is a total departure from its original title (on ?Mechanism of Human Dermal Fibroblast Motility?), since our discovery of the keratinocyte-secreted form of heat shock protein-90alpha (Hsp90?) as a potent pro-motility factor and a novel wound healing agent by our laboratory in 2007 (Li et al, EMBO J). The development of human recombinant Hsp90? protein as a new treatment for (chronic) diabetic foot ulcers entered its industrial (GMP) phase in 2013 and is under preparations for clinical trials. During the previous funding cycle of Hsp90?, we established a new pig wound healing model for burns that recapitulates the clinical characteristics of burn wounds in humans. Using this model, we have made and reported a new discovery for topically applied Hsp90? to become potentially the first therapeutic treatment of burn wounds (Bhatia et al, Molecular Therapy, 2016). Here is the reason why. Burn injuries are different from all other (acute or chronic) types of wounds by going through an unique event of so-called secondary burn wound progression following the injury, in which a burn expands both horizontally and vertically from its initial boundary to a larger area within the first 1-2 weeks. Therefore, any effective therapeutics must show dual abilities of 1) preventing the secondary burn wound progression and 2) thereafter promoting burn wound re-epithelialization (i.e. closure). Currently there is no FDA-approved therapeutics for burns. We reported that topically applied Hsp90? protein is such a dual functional therapeutics that promotes burn wound healing. First, Hsp90? prevents the secondary burn wound progression by protecting the surrounding cells from undergoing heat-induced Caspase-3 activation and apoptosis. Thereafter, Hsp90? accelerates burn wound healing by stimulating keratinocyte migration-led re-epithelialization, leading to wound closure. This is the first report for a single polypeptide that shows such dual therapeutic functions as required for effective treatment of burn wounds. The goal of this continuation proposal is to elucidate 1) how the secondary burn wound progression takes place, i.e. necrosis versus apoptosis, and 2) how topical Hsp90? prevents secondary burn wound progression. Finally, we will establish a new therapeutic entity (NTE), called Fragment-8, of Hsp90? for drug development. Accomplishment of these preclinical studies will lay the foundation for clinical trials. 1